The present invention relates generally to communicating audibly with unequipped listeners, and, more particularly, to communicating audibly inside a compartment located at a distance from an audible source by modulating ultrasonic carrier waves with audible communication.
In recent years in the U.S., there are typically 16,000 fatal multiple-vehicle collisions See Eberhard, C. D. et al; Automotive Engineering March 1997, pp. 86-90; Miller, T.; Accident Analysis and Prevention Vol. 23 No. 3 ppl. 343-352 1997 and The U.S. Statistical Abstracts. The following five categories of multiple-vehicle collisions had direct annual monetary costs of:
Approximately 70% of the cross-path collisions took place where signs and signal were installed. The Federal Highway Administration recognized the problem in 1999 when they issued new standards mandating enhanced sign and signal visibility. Frustrated municipalities are changing their laws and investing in automatic cameras which photograph and then ticket drivers who xe2x80x9cblow throughxe2x80x9d red lights.
In spite of arrays of flashing lights, rumble strips and other devices, turnpike toll booths need to be surrounded with concrete fortifications and are regularly the site of deadly rear-end collisions. Turnpikes are also the sites of deadly collisions with vehicles that have entered traveling in the wrong direction.
The U.S. Statistical Abstracts reports that there are 700 deaths and 30,000 injuries in highway construction zones. Drivers often fail to respond to numerous vehicle-mounted and roadside warning devices and crash into highway work crews at full speed. This is such a problem that many jurisdictions require highway work crews and their vehicles to be followed with crash-barrier trucks designed to absorb the impact of a crash from behind to save highway workers lives.
The reduced driving ability of the rapidly aging U.S. population is expected to make all this worse. In anticipation of the aging problem, the Federal Highway Administration (FHWA) this year issued guidelines for signs, signals and highway layout to deal with the older driver problem. Particular attention is being paid to standards for the how much light signs reflect when illuminated at nightxe2x80x94the xe2x80x9cretroreflectivityxe2x80x9d of the signs.
In attempting to solve these problems, there is the danger of visual and audial pollution. This can be witnessed at an accident site where the wreckers, ambulances, fire and law enforcement vehicles are all outfitted with strobe lights. This can have a stupefying effect on passing drivers. Some jurisdictions have had to reduce the intensity of their LED traffic lights due to complaints from the public. Installing intense lighting and attention-getting coloration on every vehicle as well as on every sign and signal is unlikely to be accepted by the public. Sound emitted from rumble strips in roadways and well as audible blind-pedestrian crossing aids have been opposed by the public living nearby and their use has had to be curtailed or eliminated.
So there is the seemingly paradoxical need for a more intense means of warning, if not, a means of jarring, dangerously approaching drivers, while avoiding disturbing the majority of drivers who are approaching safely.
Research into vehicle-borne collision avoidance devices Smith, D.; Effective Collision Avoidance Systems for Light Vehicles, A Progress Report; Proc. ITS 2000, Intelligent Transportation Society of America, Boston May 2000, reports that automobile drivers react better to audible notifications than to visual ones. The literature on television advertising points to the superiority of sound over images. Trout, J.; The New Positioning; McGraw Hill NY, 1996; reports research showing the mind is able to understand a spoken work in 140 ms while 180 ms is required to understand a written word. The understanding of the written word fades in one second while the understanding of a spoken word lasts for 4 or 5 seconds. U.S. Army research, reported on by Trout, has shown that the intonation of speech can significantly affect the rate of information absorption.
Sound is used in traffic warning systems. For example, every vehicle is outfitted with a horn. Railroad crossing gates and toll-taking machines sound bells under certain conditions. Pedestrian crossings lights outfitted for blind pedestrians transmit sound to aid the blind pedestrian. Emergency vehicles are equipped with sirens and other sound emitting devices. Construction machines emit sounds when they are backing up. The effectiveness of these devices is limited by their inability to aim sound in a particular direction and their inability to focus it on a particular vehicle or pedestrian. This limitation is simply due to the need for a sound-projecting device, such as a horn, to be gigantic to focus its output into a narrow wave. An aperture with dimensions on the order of 50 wavelengths is needed to form a wave of a few degrees width. Since speech has frequency components as low as 300 Hz which implies sound with a 1-meter wavelength. To form 3xc2x0 wide waves of 1-meter wavelength sound would require a horn with dimensions on the order of 50 meters!
Tanaka et al (U.S. Pat. No. 4,823,908) discloses directional speakers able to focus sound in a particular region of a large hall. These solve the directivity problem by using ultrasound whose wavelength in air is on the order of 5 to 10 millimeters. This implies a sound emitting aperture, to achieve 3xc2x0 wide waves, of 8-to 16-centimeter dimensions. The audible message modulates the amplitude of the ultrasonic carrier wave in a way that is similar to what takes place with AM radio. Nonlinear properties of air in the presence of intense sound waves are used by Tanaka et al to demodulate the ultrasonic carrier and produce audible sound from the highly focused ultrasonic carrier waves. The sound emitter disclosed by Tanaka et al uses a complex baffling system which is unsuitable for mounting on a traffic control sign or signal or on a vehicle. Unfortunately, their technique yielded unacceptably high levels of harmonic distortion.
It is therefore an object of this invention to significantly improve the effectiveness of traffic control systems by giving them a means of communicating audible messages into the sealed passenger compartment of conventional approaching vehicles.
It is further an object of this invention to exploit the superiority of sound communication over visual communication.
It is further an object of this invention that the devices should be electrically compatible with and mount easily onto existing traffic control systems such as signs, signals and vehicles.
It is further an object of this invention to enable vehicles to communicate with other vehicles such as those that are approaching dangerously for the conditions at hand.
It is further an object of this invention for vehicles to communicate with pedestrians or the drivers of vehicles potentially in the path of movement of the vehicle issuing the warnings.
It is further the object of this invention to automatically control the acoustic projector""s direction of transmission and the range of the focal point of the sound wave by coupling it with radar devices which measure direction, range and other characteristics of targets by analyzing skin reflections received from the targets.
It is a further object of this invention to communicate audible messages into a localized region without disturbing the whole area around the localized region.
It is a further object of this invention to delineate channels of movement such that unequipped people either walking or riding on a vehicle who depart from a channel will receive audible communication directing them back into the channel.
It is further the object of this invention to monitor ambient atmospheric conditions and modify the parameters of sound transmission as condition change.
It is a further object of this invention to provide a means to focus sound onto the upper window of a building from a distance and communicate with people located inside.
The objects set forth above as well as further and other objects and advantages of the present invention are achieved by the embodiments of the invention described hereinbelow.
This invention improves the ability of traffic control systems such as signs, signals, and officials, near roadways as well as vehicle-mounted lights and other visibility enhancers to communicate their messages to approaching vehicles. If an approaching vehicle is unresponsive, the intensity and urgency of the warning can be increased to the point of jarring the unresponsive driver or pedestrian. This is accomplished with a range sensing device, such as a radar system, which monitors approaching traffic and provides feedback on how well an approaching vehicle is reacting to the communications that the signs and signaling devices are presenting.
Vehicle drivers, pedestrians and others often fail to react to visual communications because they are inattentive, distracted, intoxicated or physically impaired. Research has shown that audible communication is superior to visual communication. This invention will give an audible voice primarily to traffic control devices as well as the ability to focus that voice on a particular vehicle or pedestrian as opposed to everyone in the general area.
The following examples of use of this invention are for purposes of examples and not as a limitation on the invention""s use. For example, the invention can be used for example with: xe2x80x9cSTOP xe2x80x9d and xe2x80x9cWrong Wayxe2x80x9d signs; traffic lights at intersection curve ahead signs; speed limit signs; flagman or police officers guarding highway work zones; tail, brake and side lights on the rear of land vehicles; pedestrian crossing signals; a directed warning siren or vehicle backing indicator; and vehicles trailing a vehicle traveling in snow or fog.
In addition, the present invention could be used with for example: navigational marks at sea; navigation lights on watercraft, and watercraft traveling in fog or other low visibility situations.
The invention can also be used by fire and other public safety personnel to communicate with people behind the closed windows of a building.
The invention can also be used in aviation applications for ground and air traffic control. Aircraft taxiing to and from the terminal, runway, and maintenance hanger can be contacted by the control tower or specially equipped aircraft with greater speed and accuracy than the current reliance on radio transmission and reception. In-flight near misses will be eliminated with aircraft equipped with the present invention. Audio communication in the cockpit will no longer rely on the radio being turned on or being tuned to the correct frequency.
In general, the invention utilizes ultrasonic carrier waves that are demodulated, after a period of time, when they encounter and then compress a window whose stress-to-strain relationship is nonlinear, in order to exploit the propagation of the audible sounds, resulting from the demodulation process inside the window glass, into the air-filled compartment the window encloses. The intersection of a large number of modulated ultrasonic carriers at one point in open air can drive the air into saturation which will also demodulate the carrier waves. This permits the establishment of boundaries for channels of movement for pedestrians or vehicles that will direct unequipped errant travelers back into the channel of movement.
For a better understanding of the present invention, together with other and further objects thereof, reference is made to the accompanying drawings and detailed description and its scope will be pointed out in the appended claims.